The present invention relates generally to a roof-mounted snow guard assembly to retain accumulated snow and prevent damage and injury caused by snow sliding off the roof surface, and more particularly, to an improved mounting block for securing such snow guard assemblies to a metal roof seam.
Snow guard assemblies have long been used for inhibiting and directing the movement of snow and ice across selected or pitched areas of roofs, as a preventive measure to mitigate the damage caused by migrating and falling snow and ice accumulations. An early application of snow guard assemblies is taught in U.S. Pat. No. 42,992 to Howe, which issued May 31, 1864. Recently, snow guard assemblies have increased in popularity, and currently several snow guard mounting assemblies serve to hold snowloads on roofs. Relevant examples include U.S. Pat. Nos. 5,613,328, and 5,732,513, each to Alley, each of which is herein incorporated in its entirety by reference.
Changing weather conditions, such as high winds or cyclically varying temperatures, create an environment that can induce physical changes in the accumulated snow, and give rise to the conditions tending to cause a snowpack to slide off of a sloped roof. Dislocated snow and ice often cause damage to surrounding property and, in some cases, the sliding snow can cause serious bodily injury; The problem of sliding snow is particularly prevalent on metal roofs. Metal roofs offer many structural advantages, such as strength and durability. However, because metal tends to absorb environmental heat, even a minimal amount of panel expansion or contraction exacerbates the conditions leading to snow slides. Furthermore, metal roofs generally afford little surface friction, which is also conducive to snow slides.
The increasing popularity of construction incorporating metal roof materials also poses particular problems with respect to attaching snow guard assemblies. A typical metal roof comprises a plurality of juxtaposed metal panels typically having substantially perpendicular edges that abut to form a joint therebetween. The perpendicular edges of the abutting panels are each crimped together and/or bent downwardly over each other forming a sealed seam which both connects the roofing panels and prevents fluid communication in between the panels and to the area beneath the roof panels,.
In snow guard assemblies for seamed metal roofs, the mounting block assembly is typically secured to the roof seam using a coupling element, such as screws or bolts. These screws or bolts generally pass through a sidewall of the mounting block seated around the seam, and extend inwardly, to contact the roof seam. However, screws and bolts tend to puncture, abrade, or otherwise damage the surface coating of the metal roof seam seal when tightened to securely fasten the mounting assembly. Holes or fissures thusly created during installation and use, and which remain after removal of the mounting assembly, destroy the hermeticity of the metal roof, and allow water to permeate the seam even while the snow guard is still attached. The water tends to attack the exposed metal beneath the damaged surface coating, creating stains, such as rust stains. This water damage weakens the metal and diminishes the intrinsic aesthetic qualities of metal roofs.
Prior attempts to address this problem include using a mounting block capable of being attached to a metal roof, as described U.S. Pat. No. 5,613,328. In order to attach the mounting block to the seam, a ball and set-screw is provided, such that the curved surface of the ball, rather than the threads of the screw, engages a portion of the roof seam. As the screw is tightened to attach the mounting block, the ball forms a pocket in the engaged portion of the seam such that the mounting block can be secured to the roof without piercing or tearing the seam.
Although this method of attachment is an improvement over the prior art attaching means, drawbacks remain. For example, the entire holding force per coupling means is limited to the contact area between the seam and each ball, which is only a singular, independent contact surface. Because such a design requires that the entire contact force be applied through a single contact surface on each ball, the total amount of static holding force (which is equal to the summation of the holding forces of each individual contact surface) is determined by the number of balls engaging the roof seam. Thus, the net holding force available for holding the mounting block in place is significantly limited, and sliding will occur if the force of the snow load exceeds the friction force at that singular point of contact.
Yet another drawback of the ball and set-screw assembly relates to the occasional rotation of the ball in conjunction with the turning of the set screw instead of gripping to form a stationary contact surface with the metal seam. This unwanted turning gives rise to damage on the contact surface of the seam, and effectively reduces the benefits of employing a ball and set-screw coupling means.
Another attempt to attach the mounting block to a metal roof seam involves the cam-like gripping means disclosed in U.S. Pat. No. 5,613,328 to Alley, the entirety of which is incorporated by reference herein. The cam is a small gripping member, whose length is not significantly greater than its width, which is positioned in a chamber on an internal side of the groove of the securing block and secured at one end. In one case, the securing block is slid along the roof seam in a direction that causes the unsecured end of the cam to catch the seam, swing out from the chamber and deform the metal roof seam, at which point the cam is locked in place using a screw. In this manner, the dented seam is gripped between the cam and a cavity located on the opposite side of the groove of the securing block therefrom. In another case, a set-screw and ball bearing configuration engages the unsecured end of the cam within the chamber, forcing the cam out of the chamber and into the groove, such that the dented seam is gripped between the cam and an opposing cavity on the other side of the groove.
While the cam, rather than a set-screw or ball bearing, contacts the metal roof seam and offers some protection for the metal roof seam, there is still room for improvement with respect to increased protection and gripping power. First, the effective gripping force is somewhat limited by the cam configuration. That is, damage can occur at the point of contact between the roof seam and the cam if too much force is used on the cam, or under the stress of a heavy snow load, because the pressure applied by the cam on the metal roof seam is essentially concentrated at that point of contact. Second, no substantial mechanical advantage with respect to gripping power is offered over the standard ball and set-screw assembly because the length of the cam is not significantly greater than its width.
Another drawback associated with prior art mounting block assemblies for snow guard assemblies relates to corrosion caused by the contact between the metal roof seam and the metal groove of the mounting block, in conjunction with the normal exposure to high degrees of moisture experienced by roofs. The corrosion is a result of a galvanic reaction between the metal roof, which is typically copper, and the metal of the mounting block, which is typically aluminum. This can lead to many harmful conditions, both cosmetic and structural, including unsightly deposits on the roof panels and a weakened coupling between the seam and snow guard assembly. Additionally, corrosion and moisture infiltration eventually degrade the hermeticity of the metal roof.
Efforts to combat corrosion caused by galvanic reactions include fabricating the mounting block using a non-reactive metal, such as stainless steel. However, using stainless steel instead of aluminum significantly increases overall manufacturing and consumer costs, and does not address the problem of moisture communication and physical harm to the surface of the seam caused by fastening with screws or bolts. Another attempt to combat reactivity involves using a non-corrosive insert as an interface in the metal groove of the mounting block, between the mounting block and the roof seam, as described in Applicant""s pending application Ser. No. 09/397,938, the entirety of which is incorporated herein by reference. However, such non-reactive inserts do not afford the seam protection from invasive coupling means, since the coupling means penetrate the inserts and directly contact the seam.
Thus, it would be desirable to provide a cost effective snow guard assembly having a means for securing a mounting block assembly onto a metal roof seam which prevents physical breach of the seam integrity by a coupling means, and which reduces detrimental galvanic reactions between the securing means and the metal roof seam, to better preserve the structural fortitude and hermeticity of the metal roof. Further, it would be desirable to provide a snow guard assembly having a means for securing a mounting block assembly onto a metal roof seam with increased gripping efficiency, whereby the amount of force required to ensure a stable connection does not exceed that which harms the metal roof seam.
It is an object of the present invention to overcome the drawbacks of the prior art, particularly to provide a snow guard assembly having a mounting assembly having a means for attachment with increased gripping efficiency, but which does not compromise the surface integrity of the metal roof seam or otherwise threaten the hermeticity of the metal roof.
In accordance with one embodiment of the present invention, a snow guard system adapted to be attached to a metal roof seam by a mounting assembly is provided. The mounting assembly includes a mounting block having a seam-receiving groove formed in a bottom surface thereof, partially defined by a first internal side, an opposed second internal side, and an upper internal side interposed therebetween, wherein the upper internal side is spaced apart from the bottom surface of the mounting block in a first direction. The seam-receiving groove extends longitudinally from a front end of the mounting block to a back end thereof in a longitudinal direction of the mounting block substantially perpendicular to the first direction. A first channel is also included, formed in the first internal side of the seam-receiving groove and extending in the longitudinal direction from a first end thereof to an opposed second end thereof. The mounting assembly further includes a lever member disposed within the channel. The lever member includes a first end and an opposed second end defining a length, L, extending therebetween in the longitudinal direction, and a first side and an opposed second side defining a width, W, extending therebetween in a second direction substantially perpendicular to the first direction and the longitudinal direction. Further, L is greater than or equal to 3W, and second side is of the lever member adapted to contact a metal roof seam preferably includes at least one protruding portion.
The mounting assembly also includes a pivot member for pivotally securing one of the first and second ends of the lever member such that the other end thereof is freely translocatable from a position within the channel to a position within the seam-receiving groove along the second direction toward a central axis of the seam-receiving groove. A coupling element is also included, having a terminal end extending through a first side of the mounting block and adapted to move inwardly toward the central axis of the seam-receiving groove and penetrate the channel portion to engage a portion of the lever member proximate the other end thereof.
Preferably, the second internal side of the seam-receiving groove further includes one of a recess or a protrusion substantially axially aligned with the pivotally secured end of the lever member across the central axis of the seam-receiving groove. The preferred lever member further includes one of a recess or a protrusion on the second side thereof, substantially and preferably proximate the pivotally secured end thereof. Suitable materials for the lever member include, but are not limited to, stainless steel, aluminum alloys, anodized aluminum, copper and copper alloys. At least the second side of the lever member is coated with a corrosion-resistant, non-metallic coating. Suitable materials for the corrosion-resistant, non-metallic coating include, but are not limited to urethane, epoxy, plastic and aluminum oxide.
More preferably, the seam-receiving groove includes another channel portion formed in the first internal side thereof longitudinally spaced apart from the first channel in the second direction and extending in the longitudinal direction from a first end thereof to an opposed second end thereof, another lever member disposed within the other channel, another pivot member for pivotally securing one of the first and second ends of the other lever member such that other end thereof is freely translocatable from a position within the channel to a position within the seam-receiving groove along the second direction toward a central axis of the seam-receiving groove, and another coupling element having a terminal end extending through a first side of the mounting block.
In accordance with another embodiment of the present invention, a snow guard system is provided, incorporating a mounting assembly including a mounting block having a seam-receiving groove formed in a bottom surface thereof. The seam-receiving groove is partially defined by a first internal side, an opposed second internal side, and an upper internal side interposed therebetween, and the upper internal side is spaced apart from the bottom surface of the mounting block in a first direction. The seam-receiving groove extends longitudinally from a front end of the mounting block to a back end thereof in a longitudinal direction of the mounting block substantially perpendicular to the first direction. The mounting assembly further includes a first channel formed in the first internal side of the seam-receiving groove and extending in the longitudinal direction from a first end thereof to an opposed second end thereof, and a second channel formed in the second internal side of the seam-receiving groove and extending in the longitudinal direction from a first end thereof to an opposed second end thereof. A first lever member disposed within the first channel is also included, having a first end and an opposed second end defining a length, L1, extending therebetween in the longitudinal direction, and a first side and an opposed second side defining a width, W1, extending therebetween in a second direction substantially perpendicular to the first direction and the longitudinal direction, wherein the second side is adapted to contact a metal roof seam. Further, a second lever member disposed within the second channel, includes a first end and an opposed second end defining a length, L2, extending therebetween in the longitudinal direction, and a first side and an opposed second side defining a width, W2, extending therebetween in a second direction substantially perpendicular to the first direction and the longitudinal direction, wherein the second side is adapted to contact a metal roof seam.
The mounting assembly also includes a first pivot member for pivotally securing the one of the first and second ends of the first lever member such that the other end thereof is freely translocatable from a position within the first channel to a position within the seam-receiving groove along the second direction toward a central axis of the seam-receiving groove. Further, a second pivot member is provided for pivotally securing one of the first and second ends of the second lever member such that the other end thereof is freely translocatable from a position within the channel to a position within the seam-receiving groove along the second direction toward a central axis of the seam-receiving groove. A first coupling element is also included, having a terminal end extending through a first side of the mounting block and adapted to move inwardly toward the central axis of the seam-receiving groove and penetrate the first channel to engage a portion of the first lever member proximate the other end thereof. Further, a second coupling element is included, having a terminal end extending through a second side of the mounting block and adapted to move inwardly toward the central axis of the seam-receiving groove and penetrate the second channel to engage a portion of the second lever member proximate the other end thereof.
Preferably, the first lever member further includes at least one of a protrusion and a recess proximate the pivotally secured end thereof and substantially aligned with one of the ends of the opposed second lever member in the second direction across the central axis of the seam-receiving groove. Additionally, the second lever member preferably includes at least one of a protrusion and a recess on the second side thereof and proximate the pivotally secured end. Preferably, the protrusions and recesses of each lever member correspond such that the recesses align with the respective opposing protrusions. The respective opposing recesses are preferably axially offset from one another along the longitudinal direction, and the respective opposing protrusions are likewise preferably axially offset. It is also preferred that the first channel is substantially aligned with the second channel such that the first and second channels oppose one another in the second direction across the central axis of the seam-receiving groove. Alternately, the first channel is offset from the second channel in the longitudinal direction such that the first and second channels do not substantially axially oppose one another in the second direction across the central axis of the seam-receiving groove.
Preferably, the mounting assembly also includes a third channel formed in one of the first and second internal sides of the seam-receiving groove extending in the longitudinal direction from a first end thereof to an opposed second end thereof. A third lever member is preferably disposed therewithin, and a third pivot member is provided for pivotally securing one of the first and second ends of the third lever member such that the other end thereof is freely translocatable from a position within the third channel to a position within the seam-receiving groove along the second direction toward a central axis of the seam-receiving groove. Further, a third coupling element is included, having a terminal end extending through a corresponding side of the mounting block and adapted to move inwardly toward the central axis of the seam-receiving groove and penetrate the third channel to engage a portion of the third lever member proximate the other end thereof.
More preferably, the mounting assembly further includes a fourth channel formed in the other internal side of the seam-receiving groove, and a fourth lever member disposed therewithin. A fourth pivot member is also provided, positioned proximate one of the first or the second ends of the fourth lever member, as well as a fourth coupling element extending through a corresponding side of the mounting block. The fourth coupling element is adapted to move inwardly toward the central axis of the seam-receiving groove and penetrate the fourth channel to engage a portion of the fourth lever member proximate the other end thereof.